The present invention relates to a workbench and, more particularly, to a workbench which includes a workpiece supporting panel carried by a trestle, with a clamping means for enabling a rigid attachment of a manually operated machine tool such as, for example, a circular saw, a compass saw, or a router, mounted on an underside of the supporting panel, and with the supporting panel including at least one cutout or opening for accommodating a portion of the machine tool such as, for example, a saw blade or cutter.
A variety of workbenches have been proposed wherein it is possible, for example, to convert a mobile or portable circular hand saw to a stationary circular table saw whereby the utility of the mobile or portable hand saw for persons working at home is considerably expanded since it is possible to convert the portable machine unit and associated power drive mechanisms with a static or stationary structure.
However, a disadvantage of conventional workbenches resides in the fact that the workbenches must be turned over to enable a mounting of a machine tool in order to provide access to an underside of a workpiece support panel of the workbench. During this mounting procedure, a topside of the supporting panel must be placed on separate supporting members so that an adequate free space remains for the tool projecting through the cutout or opening of the supporting panel; therefore, a retrofitting of conventional workbenches is always accompanied by considerable expenses. A more practical saw-workbench is shown in U.S. Pat. No. 4,465,114.
The aim underlying the present invention essentially resides in providing a workbench of the aforementioned type wherein the mounting of the manually operated mobile or portable machine tool to an underside of a supporting table of a workbench is substantially simplified.
In accordance with the present invention, the supporting panel of the workbench can be swung or pivoted from an operative position into a mounting position by rotating the supporting panel through an angle of 180.degree. with a locking device for both turning positions, that is, the operative and mounting positions, being arranged at a trestle of the workbench. After a pivoting of the supporting panel into the mounting position, the underside of the supporting panel is freely accessible at a convenient mounting level and the machine tool can be placed on the supporting panel without any auxiliary means and fixed in place by way of a clamping device. Of course, between the floor and the supporting panel there is always an adequate free space for the tool of the machine tool and, due to the provision of the locking device for both turning positions, an inadverent swinging or pivoting of the supporting panel, together with the not as yet fixed machine tool is prevented during the mounting process of the machine tool.
According to advantageous features of the present invention, the supporting panel may be arranged at the trestle in a manner of a double lever and may, in the operative position, rest on one end of the trestle, while the other end of the supporting panel may be elastically bent in an upward direction by the locking device. By virtue of this arrangement, the workbench may be set up in a very compact fashion since no additional space is required for the mounting position of the supporting panel. In the operative position, the supporting panel is supported at three points, namely, at the trestle supporting point, at the pivot axis, and at the locking device so that the supporting panel can withstand even relatively high stresses.
Since, in accordance with the present invention, the supporting panel can be elastically bent in an upward direction by the locking device, a fixing or securing with respect to the trestle is obtained which is completely without play and which is insensitive to vibrations. With a rigid cast supporting panel, the upward flexing is in the order of tenths of a millimeter, whereas, with a more lightweight sheet metal supporting panel, the upward flexing is in the order of halves of a millimeter, whereby a guidance of the workpiece is not adversely affected. By elastically bending the supporting panel, the fixing of all parts secured to said panel, e.g. the machine tool, becomes better.
In accordance with still further features of the present invention, the supporting panel may be of a rectangular or square configuration and pivotable about an axis lying on or near one of an axis of symmetry thereof. Moreover, according to the invention, the supporting panel rests, in the operative position, with one end rim or edge in parallel to the pivot axis, on a stop of the trestle, and the locking device is adapted to engage in a zone or area of the opposite end rim or edge of the supporting panel.
Advantageously, according to the present invention, the stop may be fashioned as an abutment strip affixed to the trestle and aligned in parallel to the end rim or edge on a side of the stop, and the pivot axis may lie on a side facing away from the abut strip, a certain distance removed beside the corresponding axis of symmetry of the supporting panel. The provision of the abutment strip ensures a very broad, stable resting position of the supporting panel. By virtue of an offset arrangement of the pivot axis, it is possible for the end rim or edge, lying originally on the side of the locking device, to swing or pivot freely, without removing a possibly present parallel stop, past the abutment strip during the turning or pivoting of the support panel.
According to the present invention, the supporting panel is capable of being urged against the stop by the locking device and, preferably, the locking device includes at least two eccentric levers located on both sides of the supporting panel, mounted to lateral frames of the trestle encompassing the supporting panel, with the levers causing the supporting panel to be pressed from a loose or free unrestrained resting position against the stop.
Advantageously, in accordance with the invention, the trestle includes four legs attached to ends of two lateral frames, with the four legs on the side of the stop being joined by the abutment strip, and the opposite legs being joined by a cross strut lying at a lower level. The two lateral frames, the abutment strip and the cross strut form an inherently closed frame, whereby the trestle, in spite of the pivotability of the supporting panel, has a greater inner rigidity. The lower-level arrangement of the cross strut makes it possible to effect the necessary free swinging or pivoting of the supporting panel.
It is also possible in accordance with the present invention for the supporting panel to include several cutouts or openings for accommodating tools of different machine units thereby further simplifying a retrofitting of a workbench since any desired machine unit can be placed and mounted directly at a predetermined location on the supporting panel without requiring any further adapter elements or similar means.
Moreover, according to the present invention, the cutouts or openings in the supporting panel may be respectively arranged approximately along the pivot axis and the axis of symmetry of the supporting panel disposed in parallel thereto, in a side-by-side relationship. In this manner, all cutouts or openings are located in a central region of the workbench so that there is always an adequate supporting surface for enabling a guidance of the workpieces. Since the cutouts or openings are arranged side-by-side along the pivot axis, the supporting panel, is merely weakened by a single cutout, as the conventional workbenches, in a bending zone under great stress, that is, a central zone between the two lateral frames, whereas, the cutouts or openings arranged beside the first-mentioned cutout exert practically no negative effects with regard to the rigidity of the panel.
In accordance with still further features of the present invention, each of the eccentric levers include a bearing pin unilaterally flattened along a portion of a longitudinal direction thereof, with the flattened pin zones being inserted as eccentrics in openings provided in downwardly extending side walls of the supporting panel. Advantageously, the side walls are provided at respective opposite longitudinal ends with a second opening for enabling a fixing of the supporting panel in the mounting position.
The eccentric levers may, in accordance with the present invention, be provided with one-armed operating levers that project at an inside approximately perpendicularly from the bearing pins, with the operating levers being oriented, in the clamping position, approximately in parallel to the supporting panel and, in the released position, projecting in an upward direction approximately perpendicularly to the supporting panel. In accordance with still further features of the present invention, it is possible to strut brace the respective legs of the trestle together by an appropriate base frame to reinforce or rigidify the trestle construction.
With workbenches of this type, a portable circular saw can be converted to a stationary circular table saw. When using it as a circular saw, it is a good idea to fit the slot-shaped opening in the workpiece supporting panel, generally made of sheet steel, with a chippable slot insert of aluminum or plastic for example. If the saw blade shifts sideways while sawing, this is quickly called to the operator's attention by the fact that the blade cuts into the slot insert, indicating that the circular saw must be realinged and reclamped firmly to the mounting plate. Using a readily chippable slot insert avoids the danger that pieces of hard metal will fly off the blade when using circular saw blades equipped with hard metal [teeth].
Accordingly, it is an object of the present invention to provide a workbench construction which avoids, by simple means, shortcomings and disadvantages encountered in the prior art.
Another object of the present invention resides in providing a workbench which simplifies the mounting of mobile or portable machine tools thereon.
Yet another object of the present invention resides in providing a workbench which enables a mounting of mobile or portable machine tools without requiring considerable expenses for retrofitting of the machine tools.
A still further object of the present invention resides in providing a workbench which is simple in construction and therefore relatively inexpensive to manufacture.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings which show, for the purposes of illustration only, one embodiment in accordance with the present invention .